The skin is a primary barrier of the human body and protects the organs in the body from stimulation caused by external environments such as a temperature, a change in humidity, ultraviolet rays, pollutants, and plays an important role in maintaining homeostasis such as regulation of body temperature. The keratin, which is located at the outermost part of the skin, is a tissue formed by a change in cells of the skin, and consists of completely dead cells. Coarse cell layers formed in the dermal connective tissue of the dermis have no vitality of cells toward the epidermis and are changed into solid and regular cell layers. The skin with this structure serves as a line of defense that protects the moisture of the body from the outermost side and defends the various substances input from outside. That is, when the surface of the skin is wounded, the rapid regenerating ability of the epidermis promotes the recovery of the wound, thereby preventing additional infection through the wound and reducing the scarring of the skin surface.
When the damaged skin tissue is reconstructed, various reactions are involved, and particularly, migration, proliferation, and differentiation of keratinocytes, detachment of damaged cells, and production of the epithelial tissue are involved. The process of wound healing is a very complex reaction involving various cells and factors, and first, the platelet is aggregated at the wound site and various cell proliferation factors such as a transfection factor, a platelet-derived proliferative factor, and an epithelial cell proliferative factor are released to stimulate vascular endothelium, phagocyte, fibroblast and epithelial cells, thereby promoting cell proliferation. At the same time, while these cells themselves self-secretively produce and secrete substances such as fibroblast proliferation, transforming growth factors, interleukin and other substances, the wound healing mechanism proceeds.
Currently, an epidermal growth factor (EGF), which is widely used as a wound therapeutic agent due to various activities, is either obtained by purification or obtained by overexpression in bacteria. It takes a lot of time, money, and labor to obtain by direct purification. Also, the over-expression method in the bacteria has a problem in that the recovery yield is very low due to the low expression level in the cells and proteolytic enzyme of the bacteria. In addition, the EGF has been reported to exhibit a low therapeutic effect on chronic wound sites, and it has been difficult to commercialize the EGF due to the high price to the efficiency due to a temperature and a short half-life due to the proteolytic enzyme.
Under such a background, development of a novel therapeutic agent having an effective therapeutic effect while minimizing side effects of conventional drugs for skin regeneration or wound healing has been required and has been actively studied (Korean Patent Publication No. 10-2015-0135743), but it is still not enough.